The Bible records God permitting and regulating polygamy among the patriarchs and kings without condemnation. If plural marriage discredits Joseph Smith, doesn’t it discredit Abraham, Jacob, and David?

The Christian reply is that the Old Testament narrates polygamy and its consistently bad results (Sarah and Hagar, Leah and Rachel, Solomon’s wives) without commanding it, that the creation account and Jesus’s teaching on marriage assume one man and one woman, and that the New Testament requires monogamy of church leaders. The LDS claim was that plural marriage was commanded by revelation as a requirement for the highest exaltation (Doctrine and Covenants 132), which is a different thing from tolerated ancient practice. The point is not that polygamy discredits Smith; it is that a doctrine commanded by revelation was later ended by revelation, which raises the question the next claim raises too.